1. Field of the Invention
The present invention relates to a light aircraft for short-distance takeoff and landing and, more particularly, to an aircraft comprising an airplane and an airship containing a buoyant gas such as helium, excellent in stability and maneuverability during ascending, descending, vertical, circuitous and level flight, and capable of shortening the distance required for the takeoff and landing thereof.
2. Description of the Prior Art
Generally, an airplane is superior in maneuverability and inferior in stability, whereas an airship is superior in stability and inferior in maneuverability. An aircraft comprising an airplane and an airship aims at maximizing the superior qualities and minimizing the inferior qualities of the two types of aircraft. Various kinds of such aircrafts have heretofore been proposed. Generally, a known aircraft takes off by filling a rear ballonet of the airship with air to move the center of the static lifting power of the airship to a front portion of the aircraft and utilizing the propulsion of a propeller of the airplane. This takeoff method results in a flight with an increased angle of attack. This flight requires much time in order for the aircraft to ascend to a given height and results in large drag of the airship, thus lowering the flight efficiency. The term "angle of attack" used herein means the angle formed between the direction of flight and the lengthwise axis of the airship.
The inventor proposed an aircraft comprising an airplane and an ovate balloon filled with a buoyant gas with the aim of enabling safe, stable and yet controllable flight, low consumption of fuel and short takeoff and landing distances (U.S. Pat. No. 3,807,661). This aircraft ascends by utilizing the propulsion of a propeller and the lift of a main plane of the airplane and operating a vertical rudder and elevators, and descends by decelerating the speed of the airplane to lower the lift of the main plane. In fact, this aircraft enjoys stabler maneuverability and shorter distance takeoff and landing due to the presence of the ovate balloon. However, since the balloon is inclined during the flight of the aircraft, the problem of an increased angle of attack which lowers the flight efficiency had not yet been solved.